AIM: To assess the changes to the superior dental arches, in the transversal direction, and the amount of inclinations in the support teeth of the Hyrax expansion appliance in patients who underwent surgically assisted rapid maxillary expansion (SARME), as well as the effectiveness of the surgical technique used. The sample was composed of 34 pairs of cast models, of 17 patients - 6 males and 11 females. METHODS: The measurements were performed on cast models, by measuring the changes on the vertical and transversal planes. The surgical procedure used was the lateral osteotomy on maxillary walls with no involvement of the pterygoid blade, osteotomy of nasal spine on dental midline (anterior central incisors), chisel separation of palatine suture, and separation of the nasal septum. The activation was initiated on the third postoperative day, consisting of two activations, one in the morning and another at night. RESULTS: There were statistically significant expansions in the regions of canines, first and second premolars, first molars, and second molars; respectively, 6.03 mm, 9.82 mm, 8.66 mm, 9.72 mm, and 5.67 mm. The evaluation of the behavior of the support teeth of the expansion appliance regarding the inclination of the dental crowns has shown that an asymmetric vestibularization had taken place, because the values found for the first molars were 6.89º (right) and 9.56º (left); the values for the first premolars were 4.74º (left) and 3.26º (right); this last value was not statistically significant. CONCLUSIONS: The surgical technique used in this research has been shown to be efficient to obtain maxillary transversal alterations, and there was dental-alveolar inclination of the support teeth of the expansion appliance.
Maxillary expansion; Orthognathic surgery; Dental casts
